Carburetor float valve control



H. A. CARLSON ErAx.

CARBURETOR FLOAT VALVE CONTROL Oct. 26, 1954 2 Sheets-Sheet l Filed Dec. 26, 1951 Y ATTORNEY 0ct.'26, 1954 H. A. cARLsoN p -rAL 2,692,766

CARBURETOR FLOAT VALVE CONTROL Filed Dec. ze, 1951 2 Sheets-Sheet 2 F|G.5. 29- 7\\\\\-{ v INVENTORS y HAROLD ACARLSON g; 4 BY JAMESTWMOSELEY Patented Oct. Z6, 1954 UNITED SATES hat NT GrFlCE CARBURETOR FLOAT VALVE CONTROL Application December 26, 1951, Serial No. 263,292

(Cl. 26l--l2 5 Claims. 1

This invention relates to carburetors for internal combustion engines and consists, particularly, in novel means for preventing flooding of the associated engine in case of surging of the fuel in the carburetor fuel bowl.

When the fuel in a carburetor constant level chamber is caused to surge, because of a change of direction or speed of the vehicle, the iloat vmay be lowered, momentarily, to permit an extra quantity of fuel to enter the bowl past the opened needle Valve. When the fuel again settles within the bowl, its level may be raised sufiiciently to cause liquid fuel to pour over the fuel nozzle and collect in the manifold. An extra rich or even a stall condition of the fuel charge may result. This adverse effect of surging is increased in proportion to the size of the fuel bowl and becomes accentuated in large, multi-barrel carburetors.

According to the present invention, a device is provided for preventing excessive opening of the fuel inlet needle valve in case of a surge. The device is responsive to relatively high suction posterior to the carburetor throttle valve, such as exists when the throttle valve is closed and the engine in operation, to prevent opening of the float operated needle valve beyond a slightly open, idling position.

In the accompanying drawings which illustrate the invention,

Fig. 1 is a side view of a carburetor embodying the invention, portions being broken away and sectioned to illustrate the underlying structure.

Fig. 2 is a detail, vertical transverse section taken substantially on line 2-2 of Fig. Kl.

Fig. 3 is an enlarged fragmentary section taken substantially on line 3-3 of Fig. 2.

Fig. 4 is a top View of the carburetor with portions broken away and sectioned.

Fig. 5 is a detail section taken on line 5-5 of Fig. 4.

The carburetor illustrated is of the four-barrel, downdraft type including a pair of forward main mixture conduits 'l and 8 and a pair of rear, auxiliary or secondary mixture conduits t and l0. A generally rectangular air inlet portion i l is provided at the top of the carburetor and is divided by a transverse partition l2. At the forward side of the partition, an unbalanced choke valve I3 is mounted on a shaft i4 which, at one end, extends into a housing l5 for automatic choke control mechanism. At its opposite end, choke shaft lll is connected by a crank it and link I1 to a fast idle cam device i8 pivoted, as at I9, to the carburetor body.

The lower ends of main mixture conduits 'i and 8 are traversed by a throttle shaft 2t. A lever 22, rigid with the end of shaft 2id, has apertures 23 for attachment to the usual accelerator linkage (not shown). The lever carries an idle adjusting screw 2d for engagement with the fast idle cam device i8 to limit the closing movement of the main throttle valves, during cold starting and warm-up, to a slightly more open position than the normal idling position. rThis type of throttle control and choke interconnection mechanism is further illustrated and described in Carlson Patent No. 2,307,486. Throttle valves (not shown) are also provided in the lower portions of auxiliary mixture conduits il and and the main and secondary throttles may be serially controlled as described in Moseley and Carlson application, Serial No. 263,291, iiled December 1951.

Surrounding the mixture conduits is the fuel bowl or constant level chamber structure including forward portion 26, in which are enclosed floats 2l and 28, and rear portion 2li enclosing floats 3@ and 3l. The pairs of floats il and 23 and 3G and 3l are rigidly connected by yoles 32 and 33, each of which, centrally, has an outward projection 3ft (Fig. 2), pivoted as at Se to depending structure 35 on bowl cover 3l'. Each projection 3i normally supports and actuates a fuel inlet control needle valve 38 located in an inlet valve seat device 33 controlling the supply of fuel to the associated constant level fuel bowl. The main supply of fuel to the carburetor is through a fitting lli located on the right-hand 1 side of the iloat bowl cover and connected to right-hand, auxiliary iioat bowl 29 by means of passage il through the bowl cover structure and with left-hand, main float bowl 26 by :means of passages t2. A supply of fuel under a few pounds pressure is maintained in the bowl inlets by means of the usual fuel pump or other pressure producing source.

Located in the central, lower portion of each float bowl are a pair of metering orifice elements, as shown at t3 in Fig. 4, through which fuel is supplied from the fuel bowls to the associated primary and secondary main fuel nozzles lill and 45, each discharging into a venturi tube :it or 4l. The main and auxiliary mixture conduits may be provided lwith idling systems (not shown) and the main metering orifices are controlled by graduated metering pins 50 carried by a cross bar 5i operated from the main thottle valves by an arm 52 rigid with a countershaft 53 and a second arm 54 on the end of the countershaft and connected by a link 55 to throttle operating lever 22. Also located in forward, main float bowl 26 is an accelerating pump including a piston 58 working in a cylinder 59 and connected to the main throttle valves by a piston stem 60, a link 6I, and an arm 62 rigid with the aforementioned countershaft 53. Fuel is drawn into the pump from bowl 26 past inlet check 63 and is discharged through an outlet passage Bil, past outlet check 65 and through discharge jets 66 into main mixture conduits I and 8. No accelerating pump or metering pins are provided in the auxiliary fuel bowl 25 and, if desired, the idling system on this side may be omitted, and it may be independent of or interconnected with the secondary, main nozzles 45. For further description of the internal mechanism of the carburetor, reference is made to our abovementioned copending application, Serial No. 263,291, filed vDecember 26, 1951.

As best shown in Figs. 2 and 3, a small cylinder 68 is formed in bowl cover structurev 3l and receives a piston 69 constantly urged downwardly by a coiled compression spring lt. The space in cylinder 68 above the piston is connected by a passage ll to one (cr both) of the main mixture conduits l and 3 posterior to throttle valve disks 2| therein. Thus, during operation of the associated engine, the suction at this point is applied to piston 69 tending to move it upwardly against spring 76. The upward motion of the piston is limited by a. pin 12. A downward projeetion I3 from piston 69 passes through the lower portion of cylinder t8, and has a lateral linger It at its lower extremity which underlies an angular lug l5 projecting from yoke 32 connecting noats 2l and 28. Since yoke 32 is connected through its projection 34 to fuel inlet needle valve 38, the suction mo-tor device formed by piston 69 and cylinder 63 is operatively connected to and assists in the control of the admission of fuel to forward bowl 2t. If desired, a similar suction control for the rear needle valve in inlet il may be provided.

In operation, when a change of speed or direction of the carburetor causes surging in the fuel bowls and, consequently, lowering of the floats, provided the engine is in operation and the main throttle valve closed, as will usually be the case, there -will be suiiicient suction applied to the upper surface of piston 69 to hold the same against stop 'l2 and support lug 'l5 and floats 2l and 23 in a position tomaintain needle valve 3B open just sufficient to supply the small amount of fuel needed for idling of the engine. Obviously, the floats will be supported, likewise, whenever the engine is idling, but this support will not be a disadvantage because of the continuous supply of a small quantity of fuel past the needle valve, even though piston 69 is supported in its uppermost position, as determined by piston stop 12.

In the present embodiment, the suction responsive mechanism acts directly upon the floats and thence, upon the fuel inlet needle valve. However, the suction device may act directly upon the needle valve, it being necessary, only, that `when less than idling suction exists in the carburetor barrel posterior to the throttle, the suction control for the needle valve permits adequate movement of the floats and/or opening of the needle valve to supply the maximum needed fuel. The invention may be modied in this and other respects as will occur to those skilled in the art and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

We claim:

l. In a carburetor for an internal combustion engine, a mixture conduit having a throttle therein, a constant level fuel supply chamber', a fuel inlet for said chamber, a control valve for said inlet, and a suction motor device responsive to high suction in said conduit posterior to said throttle for preventing full opening of said valve regardless of the level of fuel in said supply chamber.

2. A carburetor as described in claim 1 further including a stop for establishing the limit position of said inlet valve under the influence of said motor device.

3. 1n a carburetor for an internal combustion i engine, a mixture conduit having a throttle therein, a fuel chamber, a fuel inlet for said chamber and a valve in said inlet, a float in said chamber having an operative connection to said valve for normally maintaining a substantially constant level of fuel in said chamber, and a device responsive to high suction in said conduit posterior to said throttle for preventing full opening of said valve independently of the fuel level in said chamber.

4. A carburetor as described .in claim 3, in which said suction responsive device acts directly upon said operative connection between said float and said inlet valve.

5. A carburetor as described in claim 3 in which said suction responsive device includes a part for supporting said float in its inlet valve restricting position whenever idling suction exists in said conduit posterior to said throttle.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,340,876 Gilbert Feb. 8, 1944 2,448,709 Gilbert Sept. 7, 1948 2,633,342 Baker Mar, 3l, 1953 

